Carburetor structure



May 20, 1941. M. E. JONES 2,242,825

y CARBURETOR STRUCTURE I Filed Oct. 25, 1958 l v 2 Sheets-Sheet 1 May 20 1941 2 M. E. JoNEs 2,242,825

CARBURETOR STRUCTURE Filed oct. 25, 19:50' 2 Sheets-sheet 2 5:55. kd' r I 25 .f'f 25 C t i atented sta; 2i?, 1945i untreu 'stares PATENT FFlCE CARBURETOR STRUCTURE Application October 25, 1938, Serial No. 236,873

(Cl. 26h-Jil) 1 Claim.

cessively rich may produce rough operation. Suction control valves for the lidling have been suggested but these have not proved reliable or have been difficult to calibrate and main tain in proper operating condition. i

An object o? the present invention is to provide novel, simplified means for controlling the fuel i se obi s other more de? .d objects hereafter appearing are attained by the structures illustrated in the accompanying drawings in which:

Eig. l ls a side view, partly sectioned, showing nternal combustion engine carburetor.

` 2 is a section taken substantially on line Eig. 1;

c i5 View similar to Fig. 2 but showing ling fuel supply controlled by means of a le air bleed.

Fi showing still another modiiication in which the idling `fuel supply ls controlled by a submerged orifice in the constant level chamber.

The carburetor shown in Fig. l is of the down- Clrait type including an air inlet horn i, venturls mixing chamber 3, and outlet portion 3, flanged as at 5 for attachment to an associated internal combustion engine (not shown). A throttle valve 6 ls mounted on shaft 'l in the outlet portion and provided with an arm 8 at one end for manual operation. Adjacent the mixture conduit is a bowl Within which fuel is maintained at a substantiallyueonstant level by means of the'usual float controlled needle valve mechanism (not shown). Centrally located in the inner, bottom portion of 'the fuel bowl is a metering orifice member ill through which fuel is supplied from the bowl to main nozzle il, opening into the interior of the smallest venturi 2. Metering orifice nember Iii is controlled by a graduated metering l 4 is a view similar to Figs. 2 and 3, but

pin l2. carried at its upper end by a lever I3 pivotally mounted on post iii projecting above the fuel bowl. Lever i3 is operated from the throttle valve by means of a link I5 and crank I6 rigid with throttle shaft l, opposite arm 8.

An idling tube Il is mounted in `the inner wall of the fuel bowl and communicating, by means of a cross passage I8, with a vertical passage I8 containing a central restriction 20. Passage I9 connects, by meansof passages 2i and 22, with idling port 23 adjacent and posterior to the edge of the throttle valve, when closed. An air bleed is provided at 2li communicating with the idling passage anterior to restriction 20. A metering pin 25 has a graduated lower portion extending through restriction 20 and is carried at its upper end by lever i3.

Sil

Also operated from lever I3 is the usual fuel pump including piston rod 25 and pump pistonr 21 which responds to opening movements of the th utile to force an extra charge oi' fuel into the .1re conduit, through passage 26 and nozi-n operation, opening movement of the throttle valve moves lever I3 in a counter-clockwise direction (Fig. 2) to depress the pump piston and raise metering pin I2 toward its least restricting position. When the throttle valve is fully closed, that is, in its no load position, the largest portion of metering pin I2 will be Within orifice member lil and shortly before the throttle reaches its full open position, the smallest or least restricting portion of pin I2 will be moved into the orifice member to provide a rich power mixture. During the part throttle operation, metering rod I2 variably restricts the main fuel supply.

When the throttle valve is substantially fully closed, a rich mixture of fuel and air is drawn past restriction 20 to the idling port. At such time, metering pin 25 will be lifted to its least restricting position. During opening movement of the throttle valve. pin 25 Will be moved downwardly in restriction 20 and when throttle has reached the point where, under normal operating conditions, fuel will be discharged from the main nozzle I I, pin 25 will have been moved to a more restricting position so as to substantially cut down the fuel supplied to the idling port. The shape of pin 25 must, obviously, be determined by the metering requirements of the particular carburetor being calibrated. I contemplate the use of the idling fuel as a substantial factor in the mixtureproportioning throughout at least a substantial part of the throttle movement. Thus, I am enabled to control the idling mixture, as desired, by merely varying the shape and size of metering pin 25. Moreover, a. part of the idle metering pin, being constantly moved in the relatively vsmall metering orice, maintains the oriilce free of irnpeding solid and gase- V ous material.

In Fig. 3, metering pin 26a controls an air bleed 30 in idling passage I9a. In this case, both metering pins are connected `to lever I3 on the same side of the pivotal support thereof so that the eiective sizes of the respective metering orifices I and 30 are increased as the throttle valve is opened. By this means, air is progressively bled into the idling system as the throttle is opened from its idling position and pins 26a and oriiice 30 are constructed so that as the throttle is opened far enough to cause a dis,

charge from the main fuel supplynozzle, distion of the associated engine, such 4asis noticeable where the'idling system is completely cut oiI atterthe main nozzle starts to function.` Moreover, the

metering variations in both the idling and main` fuel supply systems is gradual at all times, there ybeing no sharply changing conditions as to pressures or metering restrictions. This results in a carburetor which can be readilyl manufactured inv production quantities, since the metering devices arenot particularly sensitive tofsuch variations in effectivesizes of parts and oriices as are unavoidable in high quantity production and as occur when the carburetor is exposed to dirt and abnormal temperatures during operation.v Various features o f the structures shown are not essential and these maybe -modified as will charge from the idling system will be reduced by the air bled thereinto.

` In Fig. 4 a separate metering orice member (I 33 is provided in the lower inner portion of the fuel bowl through which fuel is supplied to idling passages 3|, 32 and 22 leading to the idling port (not shown). The eective metering restriction of the idling system is varied by metering pin 26h according to the position of the throttle valve. Pins 2Gb and Z'Iare arranged so that pin 26h Vwill be moved toward its most restricting position asV thethrottle valve is opened and pin 21 will -be moved toward its least restricting position during such movement of the throttle valve. The idling 'and posterior to said throttle, a. restricting orifice element in said idling passage constituting the elective metering point therein, a graduated metering pin controlling said restricting orice, means operable with said throttle for shifting i said pin so as to progressively vary lthe eiective opening infsaid rtricting orice during substantial portions of the opening and closing'k i movements of said throttle and'to hold said pin system is like that in Figs. l and 2 including airV Y, bleed 24, except that metering restriction 33 is substituted for restriction 20 in the first form.

An important advantage of the various'arrangements is that the fuel is constantly supplied through the idling system so that it never becomes dry. Thus, whenthe throttle is suddenly closed, there is no lag or hesitation in the operain its least restrictingposition in the no load position of said4 throttle and said metering pin normally extending through sa evince to preven't clogging and said oriice ng of slightly the cooperating portion of said pin.

MALDWYN E. JONES.

4greater diameter than the maximum section of 

